Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

On 18/08/2015 18:13, David wrote:
Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R


It's fairly normal.

--- news://freenews.netfront.net/ - complaints: ---

On 18/08/2015 18:13, David wrote:
Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R



A digital meter presents almost no load on the battery, where as the
analogue one presents a load - if you test the battery with the digital
and analogue meter at the same time, it will almost certainly show thwe
voltage dropping on both.

So at no load, the voltage seems OK-ish, but when presented with a load,
it drops.

--
Toby...
Remove your pants to reply

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Tuesday, 18 August 2015 18:13:47 UTC+1, David wrote:
Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?

Because chirping uses up electricity which the detector is conserving for detecting and alarming purposes.

This allows it to remain operational and present an intermittent alarm over a longer period of time. No point in it warbling madly for an hour then dying completely if you happen to be out for that hour.

Owain

On Tue, 18 Aug 2015 12:12:36 -0700, spuorgelgoog wrote:

This allows it to remain operational and present an intermittent alarm
over a longer period of time. No point in it warbling madly for an hour
then dying completely if you happen to be out for that hour.

Or worse still on holiday.

On 18 Aug 2015 17:13:41 GMT, David wrote:

Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R

Yes.

What can happen is the ambient temperature drops, causing the terminal
voltage to droop below the "chirp" threshold.
The initial chirp draws current causing the voltage to reduce more and
the chirps continue in a vicious circle. A rise in temperature may be
enough to break the loop, but not always.
I've seen this particularly when lithium 9V batteries are used in
smoke alarms.

--

Graham.

%Profound_observation%

On 18/08/2015 21:10, Graham. wrote:
On 18 Aug 2015 17:13:41 GMT, David wrote:

Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R

Yes.

What can happen is the ambient temperature drops, causing the terminal
voltage to droop below the "chirp" threshold.
The initial chirp draws current causing the voltage to reduce more and
the chirps continue in a vicious circle. A rise in temperature may be
enough to break the loop, but not always.
I've seen this particularly when lithium 9V batteries are used in
smoke alarms.

Not only Litium. 20 approx years ago my elderly mother was disturbed at
night by chirping noises which she thought came from her phone. She
reporrted a fault to BT and one of the first questios asked was 'Do you
have a smoke alarm?' She did, close to the phone. The problem was an
alkaline battery dropping in voltage as the temprtature dropped at night.

Malcolm

On 18/08/2015 22:36, Malcolm Race wrote:


Not only Litium. 20 approx years ago my elderly mother was disturbed at
night by chirping noises which she thought came from her phone. She
reporrted a fault to BT and one of the first questios asked was 'Do you
have a smoke alarm?' She did, close to the phone. The problem was an
alkaline battery dropping in voltage as the temprtature dropped at night.


In my experience when the (alkaline) batteries start to fail in my smoke
alarms the chirping always starts at 2am/3am. Often ignored at night
the offending alarm cannot be identified in the morning after the sun
has come up and/or the central heating has kicked in.

The OP shouldn't overlook that there is also a battery in his digital
multimeter that may also be failing BUT readings tend to go high as a
DMM battery starts going flat.


--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

On Tuesday, 18 August 2015 18:13:47 UTC+1, David wrote:

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery

nominal is not actual

So the solid 8.85V is probably toast for anything that is very voltage
sensitive

only if very poorly designed

although the same article says "nearly dead" is around 5V and

yup

most devices are designed to cope with this voltage range.

no chance


NT

You need to measure them on a load, not just open ended. OK so it will use
up the battery a bit but this will give you a better handle on whether the
battery is on its way out. Basically with any multiple of one cell, the
usual way they go is that as the cells are in series, if one cell goes down
before the others, it in effect gets reverse charged through the load,
further knackering it and making it, effectively into a resistor, which
drops volts the more you load the battery.
What does puzzle me though is how any dry battery goes down if its just for
back up and not used very much. It implies it is being used, or that the
battery is a heap of crap in the first place!
I have also had pp3s that drop volts in the little rivet which holds the
spring grip connection to the battery. corrosion or something obviously.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"David" wrote in message
...
Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the backup
battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as well.
One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up the
alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix digital
meter.
One showed a solid 8.85V. Further checks showed that it was out of date in
2010.
The one from the alarm initially showed 9.04V and 9.05V with the reading
flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly decline
as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly, but a
spot reading indicated it was fine. I thought when they went, they went
down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and Zinc
Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R


--
Windows 8.1 on PCSpecialist box

On Wednesday, 19 August 2015 08:40:21 UTC+1, Brian-Gaff wrote:

What does puzzle me though is how any dry battery goes down if its just for
back up and not used very much.

Well batteries are made from chemicals which age just like everything else.
It;s lioke my grommet draw where teh grommets have 'metlted' the plasic draw and sort of stuck to the plastic, wierd.

It implies it is being used, or that the
battery is a heap of crap in the first place!

Virtually everything ages except gold it seems.

On Tue, 18 Aug 2015 20:01:37 +0100, Toby wrote:

On 18/08/2015 18:13, David wrote:
Just had the mains powered alarm chirping every now and then.
Puzzling in itself because although this should be a sign that the
backup battery is at the end of its life, why just chirp now and then?
Been doing it for the last couple of days, but only two or three chirps
every few hours.

Anyway, turned of the power to the alarms and took this one down.
Took the battery out and checked it with my old analogue meter and it
seemed to be at 9V.

Dug two possible spares out of the sod it drawer and tested them as
well. One showed around 9V and the other nearer to 10V.
Anyway, shoved the higher voltage one in and refitted and powered up
the alarm.
No chirping.
Will have to wait a day or so to confirm no intermittent chirping.

Decided to check the other batteries again with my cheapo ScrewFix
digital meter.
One showed a solid 8.85V. Further checks showed that it was out of date
in 2010.
The one from the alarm initially showed 9.04V and 9.05V with the
reading flicking between the two.
Checking again, it showed 8.85V and the voltage started to slowly
decline as I kept the meter on it.

Puzzled, I tried by analogue meter on it again.
Solid around 9V and no decline.

Tried the digital again and it showed 9.04/5V.

Tried it again and got the declining reading.

So it seems the battery was at the end of life and declining slowly,
but a spot reading indicated it was fine. I thought when they went,
they went down and stayed down.

Checking what the nominal voltage should be (I assume that this is the
same as that read by a meter) WikiPedia suggests 9V for Alkaline and
Zinc Carbon with 9.6V for Lithium.
https://en.wikipedia.org/wiki/Nine-volt_battery
So the solid 8.85V is probably toast for anything that is very voltage
sensitive although the same article says "nearly dead" is around 5V and
most devices are designed to cope with this voltage range.


As you can gather, I am puzzled by the erratic behaviour of this
particular battery.
Is this normal for 9V batteries?

Cheers


Dave R



A digital meter presents almost no load on the battery, where as the
analogue one presents a load - if you test the battery with the digital
and analogue meter at the same time, it will almost certainly show thwe
voltage dropping on both.

So at no load, the voltage seems OK-ish, but when presented with a load,
it drops.

Except that the analogue meter showed no slowly dropping voltage - it was
the digital one which showed the strange behaviour.

Thanks to all for the explanations.


Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

On Tue, 18 Aug 2015 23:15:51 +0100, alan_m wrote:

On 18/08/2015 22:36, Malcolm Race wrote:


Not only Litium. 20 approx years ago my elderly mother was disturbed
at night by chirping noises which she thought came from her phone. She
reporrted a fault to BT and one of the first questios asked was 'Do you
have a smoke alarm?' She did, close to the phone. The problem was an
alkaline battery dropping in voltage as the temprtature dropped at
night.


In my experience when the (alkaline) batteries start to fail in my smoke
alarms the chirping always starts at 2am/3am. Often ignored at night
the offending alarm cannot be identified in the morning after the sun
has come up and/or the central heating has kicked in.

The OP shouldn't overlook that there is also a battery in his digital
multimeter that may also be failing BUT readings tend to go high as a
DMM battery starts going flat.

That's *always* true on account the ADC reference voltage accuracy
becomes compromised by lack of voltage. The drop in the reference voltage
makes the test voltage appear higher than it really is. Normally, the DMM
will display 'Low Battery' well before the voltage reference becomes
compromised by an expiring battery.

I think most (if not all) DMMs choose to carry on displaying 'erroneous'
readings (along with the low battery warning) rather than simply refuse
to take any measurements under low battery conditions altogether as the
'Lesser of two evils' with the low battery warning offered by way of
mitigating this particular evil by warning the user that the accuracy may
well be compromised into a falsely higher reading, rather than leave the
user totally blind to the presence of (a potentially lethal) voltage in
the circuit under test.

ISTR that the 'standard' DMM test circuit impedances are 10 and 11
megohms on the DC voltage ranges (it may be higher on ranges above the
200v mark) whilst typical moving coil analogue meters can range from 5 to
50 kilohms per volt of the selected scale (20v FSD setting representing a
test meter impedance of 100 Kilohms to 1 Megohm) with 20 Kilohms per volt
being the more common (400 Kilohms meter impedance on a 20v FSD setting).

--
Johnny B Good